Circuit breaker testing arrangement



Sept. 17. 1940. v 5720555 I 2,214,853 mom-3mm 'rss'rme ARRANGEMENT Filed Aug. 1, 1938 Fig.1.

Inventor:

I Hns Attorney. v

polarity from the source I. The rethe circuit breaker 8 and the spark gaps in each covery voltage or the voltage induced between the contacts 3a and 3b by opening of the circuit is of such a polarity, as shown by the arrow, to tend to cause current. to pass through the source 2 in by the voltage of the source 2 may be of the same polarity as the recovery voltage across the contacts or the circuit breaker 3, suitable: cross connections may be employed, for example, as in the arrangement of Fig. 2. In this arrangementv spark gaps are provided in both connections. between the' terminals of the voltage source 2 and connection are double spark gaps. That is, they Y f s -5am terminal a. .portions' 4, and 8 lscross' connected to the termay bethreeelectrode gaps or two double-elec v.trode gaps in .As shown; there is a double. gap consisting of gap portions 4and 8 in series between the voltage-source terminal c and the circuit breaker terminal b and there is likewise a double gap'consisting of gap section 4' and gap section 8' in series between the'volte terminal d and the circuit breaker The terminal 'e between the gap niin'al a of the circuit breaker 3 through a com-,

" pleximpedance hand the terminal f between the gap sections 4' and ,8? is cross connected to the terminal a of thecircuit breaker a through a complex impedance 1'. ,It will be understood that the iinpedances I and 11' are relatively high ihjfvalue. They may madeso, that they transmit the voltages "of the points ,a and b to the points e and}! without'itime lag. .,They may, for

.2 I er current to tollowthrough an arc acrossthe example, be capacitative impedances consisting of condensers and resistorsin seriesg, 1

,A condenser 9 may bebonnected acrossthe voltage source 2' ror'maintenan'ce. or voltage an adequate length of time after thjcollapse of the spark gaps, and also to tacilitateprc'viding a more powerlul flash-over spark to'permitpowcontacts of the circuit breaker I, evenafter diniinution or voltage provided by the source 2. If desired, a closely adjusted spark gap IO'may also be provided in series with the condenser 8 for protecting it from the prolonged current. 3

In the arrangement of Fig. 2 the gaps 4 and 4' are so designed as not to'be broken down by either the additional voltage'of the source 2 alone or'the actual recovery-voltage or the break-- er 3"alone, buttobe broken'down only by the sum of the voltages. when, the circuit breaker 3 is opened and the recovery voltage appears, the potential oi. the terminal I: is transmitted to the terminal I and the potential oi the'terminal a is transmitted to the terminal e. Accordingly, the polarity of the generator 2 must .be

It will be understood that to maintain the polar- 'it-y relationships, the generatorsi and 2 should be runsynchronously. when these gaps-break down the voltages of the terminals-c and .d are connected-to the points e and I: whereupon the gaps 8 and 4' also in polarity of additional voltage passing to thepoints aand b so thatthis I .small as possible.

the testing 'frequency.

there is a reversal voltage appears across the switch contacts with the same polarity as the recovery voltage.

The construction of the complex resistances I and I callsfor particular care in view or the K unavoidable capacities cooperating therewith.v

Inbrder that there may benotime lagJthe'capaoities of the points c and I may be made as This purpose is served by the use of double spark gaps 4 and 4' by means of which the high'earth capacity of the voltage source 2 is kept away from points e and f. The

impedances l-and l may be constructed as purely ohmic resistances. However, it is preterable for protection to' connect in series condensers having alrelatively high'reactance at Complex; impe'dances such as condensers, for example, which are large in comparison with the condenser 9 may likepreferablyontheadjustment of the spark gaps 20 wise be included ,in the conductions b-c ,and I 4 and 4'. These are stressed by a-sldwly variable I additional voltage and by a sudden, e gee;-

the purpose of'the' sparkgap collapse, jthe variation of the adjustment or the sparkgaps' 4 is but slight. This'can be obviated by'a'rurther v ablylower actual recovery voltage. "Intheofsubstantial variationsfloff the calculated momentary value or the recovery voltage serving improvement of the; arrangement" in which the spark gaps 4'are constructed as controlledmultiple spark gaps, whereby the cor'itrol used is ca-" paoitive and ohmic. 1 The ohmic control,- which is determinative for the low irequencygprovides for the highest possible flash-over strength-"a1; low frequency, while the, capacitive controli-Drovides for as low a fiasheover strengthas'possi p at high frequency. The adjustment brittl spark gaps can be undertaken with "greater precisions by such means.)

Ancther arrangement for adding z volta'ge" to produce collapse of the spark gaps is illustrated in the arrangement or Fig. 3 in whlch' 'a' tran'sformer is employed. In the "arrangement (it Fig.

3 there is a" transformer H having a" p'r 'iniary I winding connected across the terminals d'a'nd' b of the circuit breaker 3 and having a"stepup'se'condary winding connected on one side-to the terminal g which islconnected throu'gh' con-, densers l2 and 12' across the double spark gap' 4, 4' and is connected'on'thepther side tethe s terminal hconstituting themidpoint of d'ov'uble spark gaps 4,f 4', The'transformer II is preferably one having'the lowest possible leakageiin rder to produce a minimum or time lag." The ratio of transformation or the. transformer] I;

may be such that the transformed recovery:

Y s is brought p to heorde'r oz magnitude thefadditmnal e 01 the s urces.

The condensers m ns-12'; are in'compari'scnwith the condenser 9 and regulateithe potential or the pointyby providingfa prede v c I termined potential distribution in thegapfsece ,theopposite to thatshown inthearrangement I v I r 1 of Fig. 1 for the gaps 4 andf4' to breakdown.

tions 4, 54'.

gaps4, 4' are stressed-substantially only by the addtional voltage 'ofthe-source, 2, and theadjustsx to i ' ment is such that the gaps do not breakdown at v opening of the this voltage. appears, then It, I however, a high recovery voltage mains fixed and one of the gap sections breaks down. The second gap section thereupon breaks downinsympathy,

In the arrangements.actually'illustrated in Figs. 1 and 2 and thus far described in connection er in'series with the tested input device 3, in a well-known manner so arranged that the auxiliary breaker is testing device 3 has disconnected the short circuit source i from the terminals of the tested device I, For example, as shown in the arrangement of Fig. 3 there may be an auxiliary circuit I! with contacts included in'the connections between the source i and the terminals b and a of the tested device and the operating mechanisms of the circuit interrupting devices 3 and i3 maybe connected together or operated simultaneously in any desired well-known manner.

I have herein shown and particularly described the potential of the terminal I: is displaced while the potential of the pointqreopened simultaneouslywhen the n a 3 certain embodiments of my invention and certain methods of operation embraced therein for the purpose of explaining its principle and showin its application but it will be obvious to those skilled in the art that many modifications and variations are possible and I aim, therefore, to

cover all such modifications and variations as fall withinthe scope of my invention which is defined in the appended claims. t I

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. An arrangement for testing circuit interrupting devices comprising in combination with 1 the circuit interrupting device to be tested, a relatively high current, low voltagesource connected thereto, a relatively high voltage source with a. pair of connections to said circuit interrupting device each of said connections including aldouble section spa 1: gap with a mid terminal, and cross connections from said circuit interrupting device to said mid terminals.

2. An arrangement for testing circuit interrupting devices comprising a pair oi test terminals to which a circuit interrupting device to be tested may be connected, a relatively high current, low voltage source connected to said terminals, a relatively high voltage source having a pair of connections to said terminals each of said connections including a double section spark gap with a mid terminal and cross connections between said test terminals and said spark gap mid j terminals.v

VITALY GROSSE. 

